Journal Article

FZJ-2017-03218

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Magnetism of monomer MnO and heterodimer FePt@MnO nanoparticles

Sun, X.FZJ* ; Klapper, A. ; Su, Y.FZJ* ; Nemkovski, K. ; Wildes, A. ; Bauer, H. ; Köhler, O. ; Schilmann, A. ; Tremel, W. ; Petracic, O.FZJ* ; Brückel, T.FZJ*

2017
Inst. Woodbury, NY

This record in other databases:    

Please use a persistent id in citations: http://hdl.handle.net/2128/14256  doi:10.1103/PhysRevB.95.134427

Abstract: We report about the magnetic properties of antiferromagnetic (AF) MnO nanoparticles (NPs) with different sizes (6–19 nm). Using a combination of polarized neutron scattering and magnetometry, we were able to resolve previously observed peculiarities. Magnetometry, on the one hand, reveals a peak in the zero-field-cooled (ZFC) magnetization curves at low temperatures (∼25 K) but no feature around the Néel temperature at 118 K. On the other hand, polarized neutron scattering shows the expected behavior of the AF order parameter vanishing around 118 K. Moreover, hysteresis curves measured at various temperatures reveal an exchange-bias effect, indicating a coupling of an AF core to a ferromagnetic (FM)-like shell. ZFC data measured at various fields exclude a purely superparamagnetic (SPM) scenario. We conclude that the magnetic behavior of MnO particles can be explained by a superposition of SPM-like thermal fluctuations of the AF-Néel vector inside the AF core and a magnetic coupling to a ferrimagnetic Mn2O3 or Mn3O4 shell. In addition, we have studied heterodimer (“Janus”) particles, where a FM FePt particle is attached to the AF MnO particle. Via the exchange-bias effect, the magnetic moment of the FePt subunit is stabilized by the MnO.

Keyword(s): Magnetic Materials (1st) ; Magnetism (2nd)

---

Contributing Institute(s):

1. Streumethoden (JCNS-2)
2. Streumethoden (PGI-4)
3. JARA-FIT (JARA-FIT)
4. JCNS-FRM-II (JCNS (München) ; Jülich Centre for Neutron Science JCNS (München) ; JCNS-FRM-II)

Research Program(s):

1. 144 - Controlling Collective States (POF3-144) (POF3-144)
2. 524 - Controlling Collective States (POF3-524) (POF3-524)
3. 6212 - Quantum Condensed Matter: Magnetism, Superconductivity (POF3-621) (POF3-621)
4. 6213 - Materials and Processes for Energy and Transport Technologies (POF3-621) (POF3-621)
5. 6G4 - Jülich Centre for Neutron Research (JCNS) (POF3-623) (POF3-623)

Experiment(s):

1. DNS: Diffuse scattering neutron time of flight spectrometer (NL6S)

Appears in the scientific report 2017

---

Database coverage:
; ; ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; IF < 5 ; JCR ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

---